The present invention relates to a radiation absorber, especially an integrated radiation absorber. Absorbers for the VHF, UHF and microwave as well as millimeter wave range are used to reduce the retroreflections of an object when illuminated by illuminating radiation. In connection with radar, the radar cross section of an object is referred to, which is the apparent extent of an object when illuminated by a radar which is satellite-borne, airborne, sea-borne or arranged on ground level. In many cases it is desirable to reduce the radar cross section. Absorbers are also used indoors in measuring rooms or in other places where undesirable electromagnetic radiation is to be reduced.
Absorbers can be of the resonant type or of the non-resonant type. Known resonant absorbers, such as so-called single foil layer absorbers, to which the present absorber belongs, usually have good radiation-absorbing capacity for radiation within a certain narrow frequency range. However, it is a great advantage if a radiation absorber can act within a great frequency range which should be easily calculatable and adaptable to the application at issue and the desiderata involved.
In many applications, including military applications, it is also most important to use absorbers which are shockproof, weatherproof and environmentally resistant. Besides it is advantageous if they can be integrated into the structure of an object and contribute to the load-carrying capacity thereof. Other desirable properties are low weight, low price and the possibility of being manufactured, without complicated special engineering, by the manufacturer of the object whose surface is to be coated. It should be possible to apply them on previously manufactured objects, which usually requires the weight of the absorber to be low.
The present invention solves all the problems described and provides an integrated radiation absorber with a wide working frequency range by being designed in the manner as is evident from the independent claim. Advantageous embodiments of the invention are defined in the remaining claims.